This proposal for the BARI Central Radiographic Laboratory describes the background of angiographic studies as they relate to coronary bypass surgery and percutaneous transluminal coronary angioplasty (PTCA) and sets forth the following sets of recommendations (1) Protocols which include quality assurance measurements, for acquisition of entry coronary left ventricular (LV), PTCA and intercurrent angiographic studies which will allow precise computer-assisted quantitation of coronary anatomy where designated; (2) Use of a computer-based coronary angiographic reporting system that is interfaced with a hand-held electronic caliper unit at each of the clinical units. This system provides a flexible format for description of differences in coronary anatomy and stenosis location, calipers for uniform and reproducible measurement of coronary stenosis severity and codification of data for rapid and easy transfer from clinical units to the Data Coordinating Center; (3) Protocol for Central Laboratory review of entry coronary, LV angiographic studies which will define: (a) coronary anatomy and stenosis location; (b) quantitation of stenosis severity using caliper methods; (c) description of stenosis morphology; (d) evaluation of potential for coronary bypass surgery and PTCA; (e) computer-assisted coronary quantitation of stenosis severity if wanted by the Steering Committee; and (f) quantitation of global and regional LV function. (4) Protocol for Central Laboratory evaluation of PTCA angiographic studies which will evaluate: (a) coronary anatomy pre-PTCA; (b) caliper measurement of coronary dimensions pre- and post-PTCA; (c) stenosis morphology post-PTCA; (d) adequacy of revascularization after PTCA and (e) computer-assisted quantitation of coronary dimensions pre- and post-PTCA. (5) Protocol for evaluation of intercurrent angiographic studies which will be analyzed at the Central Laboratory. These recommendations and protocols provide quality assurance for angiographic studies, effective data collection, expert panel review and the scientific and logistic experience required to make BARI a successful clinical trial.